Handbook of Propagation Effects for Vehicular and ... - Courses

8-22
Propagation Effects for Vehicular and Personal Mobile Satellite Systems
over the frequency range 700 MHz to 1800 MHz (described in Section 8.2). In the effort
described here, Vogel and Torrence used a similar experimental configuration employing
an antenna mounted on a tower which simulated transmissions from a satellite platform
and which radiated right hand circular polarization signals (RHCP). The receiving
antenna received RHCP over a beamwidth of 90° in both the vertical and horizontal
principal planes. As in the previous experiment, the receiving antenna inside each of the
buildings was located on a positioner that moved it in 5 cm increments over 16 spatial
positions (80 cm).
8.4.1 Experimental Description
The major components of the experiment of Vogel and Torrence were a 20 m crank-up
transmitter tower mounted on a van, a vector network analyzer (VNA), a personal
computer (PC), and a linear positioner. One of the two wideband antennas was mounted
atop the tower outside a building and the other at the positioner inside where the relative
signal levels (in dB) were determined. As previously described, the relative signal levels
were determined by comparing the levels measured interior to each of the buildings with
the reference levels measured for the unobstructed line-of-sight case outside. The PC
controlled the VNA and linear positioner, and stored the data from the VNA. The
relative signal frequency was swept between 500 MHz to 3000 MHz at 1 MHz
increments and the data were analyzed at a step bandwidth of 0.2% of the frequency. At
the low frequency end, the sampling increment was therefore 1 MHz (500 MHz x 0.002)
and at the high end it was 6 MHz (3000 MHz x 0.002). Measurements were made into
six different buildings during the Spring of 1995. The names of these buildings and
pertinent parameters are summarized in Table 8-13. The Commons, EERL, the
Farmhouse and the Motel were sites also used in the L- and S-Band investigations [Vogel
and Torrence, 1995a; 1995b] described in Section 8.3. Photographs of the exterior
buildings and floor layouts with measurement locations within each of the buildings
listed in Table 8-13 are given by Vogel and Torrence [1995c].
Table 8-13: Building names and pertinent characteristics.
Building Name
Year of
Construct.
Type
# of
Stories
Roof Type
Avg. El.
(°)
Commons Entry 1987 concrete wall 1 tar 18 7
EERL 1944 block brick 1 tar 38 6
No. of
Locat.
Farmhouse 1880 wood frame 2 metal 33 12
House 1976 wood frame 2 metal 41 10
MER 1992 glass, concrete 2 tar 26 9
Motel 1980 brick 2 composition 37 8
8.4.2 Average Signal Levels over Frequency Band and Positions
Figure 8-13 summarizes the overall relative signal loss results at the various building
locations. The mean, standard deviation, minimum and maximum values were obtained